User's Manual

22
GMSK Modem Option board
Connector
No.
Pin
No.
Function Description
Input/
Output
Connector 1
1 VCC 6V to 12V Power Input I/P
2 GND Ground
3 PTT Signal from the digital board to enable transmitter circuit of
modem board.
I/P
4 TXD_EN It ensures that the radio has stabilized in transmission
before the data is processed for modulation.
I/P
5 TX_END To finish transmission, it indicates memory buffer of Master
MCU of digital board is empty.
O/P
6 MUTE
(Busy)
Logic level input from digital board to indicate whether a
carrier is present or not
I/P
7 MODEM_EN Modem Enable input I/P
8 POWER_SAVE Power save input for modem board. I/P
9 CMD_EN It indicates that command for Modem programming is
effective.
I/P
10 CMD_IN/OUT Data Input and Output for Modem programming. I/P,
O/P
11 CMD_CLK Clock Input for Modem programming. I/P
12 MODEM_SEL It Indicates modem type to Master MCU for programming. O/P
13 RX_IN The GMSK signal input for the receiver of modem IC. I/P
14 TX_OUT The GMSK filtered Tx output signal. O/P
Connector 2
1 Serial_IN The Serial data to be transmitted is input to this pin. I/P
2
Serial_OUT The recovered asynchronous serial data output from the
receiver.
O/P
3
Busy To eliminate data loss according to buffer overrun of slave
MCU’s memory, it indicates buffer status.
O/P
4
Carrier_Detect Handshake signal for RTS control mode. It indicates
whether Slave MCU of modem has decoded data or not.
O/P
5
PTT_IN Handshake signal for RTS control mode. It requests data
transmission to Slave MCU of modem.
I/P
6 PROGRAM It’s reserved input for firmware upgrade. I/P